This invention relates to a mobile terminal, and, in particular to a system and method for efficiently converging the output power of a mobile terminal to a desired level.
A mobile terminal""s output power may be set based on instructions received from a base station, due in large part on the distance from the mobile terminal to the base station. If the mobile terminal""s output power is too low, poor uplink performance to the base station will result. If the mobile terminal""s output power is too high, the mobile terminal""s power source could be prematurely drained.
A power controller for a mobile terminal variable gain amplifier (VGA) consistent with the invention includes a feed-forward path for receiving a VGA setting and providing a VGA output. The VGA setting includes an initial VGA setting adjusted by an error signal. The power controller further includes a feedback path providing the error signal. A control algorithm in the feedback path is configured to establish the error signal in response a difference between a signal representative of the VGA output and a signal representative of a target output. The error signal causes convergence of the VGA output based on a magnitude of the difference. A mobile terminal including the power controller may receive data indicating the target output from a base station.
A method of controlling the output of a variable gain amplifier in a mobile terminal consistent with the invention includes identifying an output power level from the variable amplifier; comparing the output power level with a target level; and adjusting the output power level based on a magnitude of the difference between the output power level and the target level.